LOS ANGELES (Reuters) - The prospect of a
long awaited mega-bout between Floyd Mayweather Jr. and Manny Pacquiao
may have receded in recent years but promoter Bob Arum believes the
fight will take place, most likely before the end of 2016.

A duel between the defence-minded Mayweather and the aggressive
Pacquiao, the biggest drawcards of their generation, has long been
savored by boxing fans, if only to decide the mythical title of the
world's best pound-for-pound fighter.

Filipino Pacquiao lost much of his appeal after successive defeats
to American Timothy Bradley and Mexican Juan Manuel Marquez in 2012,
prompting talk of his possible retirement, though he has since
bounced back with two impressive wins.

"I think that fight will eventually happen," Arum, Pacquiao's
promoter, told Reuters on Thursday in a telephone interview. "We are
certainly open to the fight happening and we are prepared to sit
down with (the Mayweather team) at any time and work out terms."

Five-division world champion Mayweather, who is known for his shrewd
business acumen, had been expected to meet Pacquiao in 2010 until
negotiations collapsed over the American's demand for random drug
testing.

Mayweather, who has hinted at illegal methods by often questioning
how Pacquiao could have won world titles in an unprecedented eight
weight classes, has since said he would not fight the Filipino as
long as Arum is his promoter.

Veteran Arum, however, has his own theory about that.

"Frankly, it's the same as it always was," said the 82-year-old
promoter, who has worked with giants of the ring such as Muhammad
Ali, Sugar Ray Leonard, Marvin Hagler and Roberto Duran.

"The idea that Mayweather says, 'Well, I'm not going to fight
Pacquiao because Bob Arum is involved,' is the latest is in a whole
line of excuses.

"If you look at it from Mayweather's standpoint, he has this
unbelievable deal with Showtime (satellite television network),
paying him all this money ... so he would probably figure, 'I have
three more fights under the Showtime contract'."

STRONG FEELING

Assuming that Mayweather wins those next three fights to improve his
perfect record to 49-0 and conclude his Showtime deal, Arum has a
strong feeling that the flamboyant American would then agree to a
mega-fight with Pacquiao (56-5-2).

"He (Mayweather) would figure, 'Why don't I do those (three) fights
for the easy money and then in 2016, with my 50th fight, I could
beat the (49-0) record of (Rocky) Marciano by fighting Pacquiao',"
said Arum.

Should that bout take place, it could well be the last fight of
Pacquiao's career as the Filipino agreed earlier this week to extend
his promotional agreement with Arum's Top Rank company until the end
of 2016.

Between now and then, Pacquiao is likely to fight twice each year
and he will next step into the ring on Nov. 8, in all likelihood in
Macau and probably against his old foe, Mexican Marquez, a
four-division world champion.

"Marquez has not, as of yet, committed to the fight so we will be
talking to him in the days ahead," said Arum. "I am going to be over
in Macau next week (for a fight) and I have invited Juan Manuel and
his wife to come. I believe they will."

Marquez, who knocked out Pacquiao the last time they met in December
2012, beat welterweight Mike Alvarado by unanimous decision in his
most recent fight, last week.

Should Marquez decline the opportunity to take on Pacquiao for a
fifth time, Arum said he would probably then target Ruslan
Provodnikov of Russia as the Filipino's opponent in November.

When Pacquiao's promotional agreement with Top Rank ends at the end
of 2016, the Filipino southpaw will be 38 years old, the perfect
time for him to end his glittering boxing career.

"That's what we figured and that's why we made it to the end of
2016," said Arum. "Hopefully by that point he would have been
elected to the Philippine senate and that's very time consuming.
That would be the signal for him to hang up his gloves."